Back space device



Dec. 19, 1961 G. slM

BACK SPACE DEVICE 3 Sheets-Sheet 1 Filed June 23, 1958 INVENTOR GORDON SIM ATTOR EY Dec. 19, 1961 G. SIM

BACK SPACE DEVICE 3 Sheets-Sheet 2 Filed June 23, 1958 u L m O B W 7 4 9 9 4 2 5 5 w 5 g 4 9 MN 8 8 8 "N2 3 4 O 4 O 4. O 2

3 2 7 6 3 3 H l 6 \I/ D O 9 m n O r v i 7 0 mi 5 INVENTOR GORDON SIM Dec. 19, 1961 G. SIM

BACK SPACE DEVICE Filed June 25, 1958 3 Sheets-Sheet 3 INVENTOR GORDON SIM ATTORNEY United States Patent O fice 3,013,716 Patented Dec. 19, 1961 3,013,716 BACK SPACE DEVICE Gordon Sim, Northbrook, Iil., assignor to Teletype Corporation, Chicago, 1th., a corporation of Delaware Filed June 23, 1953, Ser. No. 743,850 8 Ciaims. (Ci. B t-129) This invention pertains to tape perforating apparatus and more particularly to means for backspacing the tape.

More specifically, the present invention is directed to an improvement in the backspacing mechanism disclosed in US. Patent No. 2,648,385 granted August 11, 1953, to J. L. De Boo. The backspacing mechanism in said patent is of the manually operated type. According to the present invention, a power operated backspacing device is provided, which is effective under the control of the backspace key in the keyboard, and comprises an electromagnet whose energizing circuit is controlled by a contact associated with the backspace keylever. The armature of said electromagnet in its released (unattracted) position acts to block or prevent the engagement of a backspace linkage system with a constantly reciproeating actuating lever. Upon operation of the backspace keylever, the circuit is established for said electromagnet which, upon energization, pulls up its armature to permit said engagement, to thereby effectuate a backspacing operation. As a non-repeat feature, an instrumentality is provided which is interposed, during the first backspace operation, between the end of the armature and one of the elements in said linkage system, to prevent further backspacing of the tape in the event the release of the key is delayed. Upon de-energization of said electromagnet, said instrumentality is withdrawn, thus restoring the non-repeat device to normal to await the next operation of the backspace keylever. As a further feature of this invention, novel means is provided for facilitating the backspacing of chadless tape, which is a species of partially perforated tape having apertures with hinged'lids, instead of fully perforated holes.

A primary object of the invention is to provide an efficient and positive means for efiecting the reverse stepwise movement of a tape.

Another object of the invention is to provide novel and effective facilities for backspacing tape having lidded apertures.

A further object of the invention is to provide a positive means for limiting the backspacing movement or" the tape to a single step upon each initiation of the back spacing operation.

A more complete understanding of the present invention may be had from the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of the backspacing mechanism according to the present invention;

FIG. 2 is a perspective view of the backspace control magnet and associated elements;

FIG. 3 is an elevational view of the backspace control magnet and associated elements in the normal rest conditio-n;

FIG. 4 is a perspective view of the rake for leveling the lids preparatory to backspacing;

FIG. 5 is an elevational view of the backspacing mechanism;

FIGS. 6 and 7 are fragmentary elevational views illustrating the backspace mechanism in various operating positions; and

FIG. 8 is a longitudinal sectional view through a perforating apparatus in which the improved back spacing mechanism constituting the present invention has been incorporated and showing the feed pawl for advancing the tape and the mechanism for selecting punches for operation.

The present invention, in its preferred embodiment, has been adapted to a perforating apparatus exemplified by the aforementioned Patent No. 2,648,385. In the drawings, only so much of the apparatus of said patent is shown as is necessary to the disclosure of the present invention. Thus, in FIG. 1, the shaft 11, sleeve 12, tapefeed-hole punch wheel 13, feed-hole die wheel 14 and tape feed ratchet 15, have their counterparts in elements 154, 155, 156, 159 and 161, respectively, of said patent. Also, in FIG. 5, the backspace eccentric 17 carried on shaft 18 is analogous to the eccentric 122 carried on shaft 13 in said patent. As described in said patent, the gear 16 is driven continuously by a suitable source of power (not shown) to rotate the shaft 18 constantly. The tape feed guide 19 (comparable to guide 164 of said patent) guides the tape 21 into position where it is engaged by the feed hole punch wheel 13.

Having reference to FIG. 5, there is journaled in the side frames 22 and 23, the shaft 11 that carries the sleeve 12 on which the ratchet 15 and the combination punch and feed wheel 13 are integrally mounted. Associated with the ratchet 15 is the tape feed pawl 24 which is mounted pivotally on an arm 25 of link 26 of a punch actuating toggle mechanism 27 comparable to the punch actuating toggle mechanism 107 shown in said Patent 2,648,385. clockwise direction about shaft 20 by a punch actuating eccentric 222 to effect a perforating operation, the pawl 24 is lowered to engage the next succeeding tooth on the ratchet 15 (it being understood that under normal tape advancing conditions, the pawl 24 is urged counterclockwise into engagement with the ratchet 15 by its spring 28) and when the link 26 is returned to its clockwise position, the pawl 24 is raised to effect the counterclockwise rotation of the ratchet 15 one angular step, to advance the tape 21 one step by means of the feed wheel. 13. In the present embodiment of the invention, the tape feed pawl 24 is provided with an arm 29 for a purpose hereinafter set forth.

The backspacing linkage system according to the present invention comprises a principal backspace member 31 mounted pivotally on a stud 32 secured to the side plate 23. about stud 32 by a spring 33 having one end affixed to the member 31 and the other end afiixed to an anchor bar 34 secured to the side plate 23. Thus, member 31 is normally held against the side plate at (FIG. 5

To the extremity of arm 36 of member 31 is pivotally I connected one end of a link 37, the other end of which is connected pivotally to an arm 38 of a composite lever 39 pivotilly mounted on a stud 41 secured to the side frame 23. Lever 39 comprises a bell crank portion including arm 38 and projection 42. (FIG. 1), and a por-' tion 43 carrying a stud 44 afiixed at one end thereof and a pair of projections 4-5 at the other end. Thus, the angularity between arm 38 and portion 43 may be adjusted with a screw driver or the like through the medium of the adiusting facilities comprising projections 42 and 45, and clamping facilities comprising a clamping screw 46 attached to the bell crank portion and a slot or enlarged hole in portion 43 cooperating with the screw 46.

Referring to FIG. 5, the backspace eccentric 17 is provided with an operating arm 47 terminating in an openended slot 48 adapted normally to cooperate slidably with the stud 44 on the composite lever 39 (see FIGS. 1 and 3). Arm 47 is provided with a shoulder 49 by means of which the backspacing operation is efiectuated, as will hereinafter appear. To the extremity of arm 36 of member 31 is also fixed a stud 51 (FIG. 1) which cooperates with arm 29 to disengage the feed pawl 24 from the ratchet 15 during the back-spacing operation.

Backspace member 31 is provided with a vertically Thus, as link 26 is actuated in a counter-.

Member 31 is normally biased counterclockwise I directed arm 52 at the extremity of which is pivotally carried, on a stud 53, a back-space pawl member 54. Member 54 is substantially U-shaped and comprises the backspace pawl 55 and a depending arm 56. Arm 56 terminates in a laterally disposed portion 57 which coacts with a latch 58 carried on a pivot stud 59 fixed to a sidewardly directed lug 60 on said arm 52. Latch 58 is normally biased clockwise about pivot 59 by a spring 61 into cooperative relation with portion 57.

Pawl member 54 is normally biased clockwise about stud 53 by a spring 62 extending between the web portion of member 54 and an extension 63 on an adjusting member 64 carried pivotally on stud 53. Member 64 is provided with a depending portion 65 adapted to cooperate with the portion 57 of member 54. Member 64 is also provided with an enlarged hole adapted to cooperate with a clamping screw 66.

As more clearly illustrated in FIG. 6, there is pivotally mounted on the stud 59, a segmental gear rack member 67, the gear teeth of which meshes with a pinion 68 formed on the end of a rake member 69 suitably journaled in the side frames 22 and 23. As shown in FIGS. 1 and 4, the rake member 69 is provided with a plurality of rake-like projections 71 (five in the present embodiment) which are adapted to register with the code hole positions in the tape 21, so that when the rake member 69 is rotated, in a manner hereinafter described, the projections 71 will act to level the tape lids 72 into the plane of the tape to facilitate the backspacing of the tape 21 through guide members 77 and 78 (FIG. 4) without tearing the lids 72. Member 67 is provided with a tail portion 73, to the hooked end of which one end of a spring 74 is connected, the other end of said spring 74 being connected to a spring post 75 secured to a brace portion 76 of member 31. Thus, spring 74 functions to bias the rack member 67 clockwise to maintain gear teeth 70 in meshing engagement with the pinion 63.

Appropriately positioned between side frames 22 and 23 and in cooperative relationship with the aforementioned backspacing linkage system comprising member 31 and associated elements including composite lever 39 and backspace eccentric 17, is an electromagnetically controlled device 81. Device 81 comprises an electromagnet 82 having an armature member 83 suitably mounted pivotaliy on a pivot rod 84. A spring 85 attached to the arm 86 of member 83 urges the armature member 83 in a counterclockwise direction when the magnet 82 is deenergized. As shown in FIG. 2, the armature member 83 is provided with sidewardly directed arms 87 and 88. Arm 87 of the armature member 83 cooperates with an arm 89 of a lever 91 mounted pivotally on a pivot stud 92 secured to a bracket 93 fixed in the apparatus. Lever 91 is provided with a laterally directed interponent portion 94 adapted to function as an inhibitor to prevent more than a single backspacing operation in response to each operation of the backspace key, as will presently appear.

Referring particularly to FIGS. 1 and 3, there is pivotally carried on the stud 44 of composite lever 39, a further composite lever 95 comprising a portion 96 and a portion 97 which are adjustably related in the same manner as the portions comprising lever 39, the clamping screw 98 being used to maintain the adjustment. Portion 96 comprises a laterally directed projection 99 adapted to coast with the shoulder 49 to effectuate a backspacing operation, as will presently appear. Portion 96 is also provided with a depending arm 101 to the extremity of which is attached one end of a spring 102, the other end of which is attached to a spring post 103 secured to lever 91. Lever 91 and composite lever 95 are thus biased attrahently by the spring 102 for a purpose which will presently appear. Portion 97 of the composite lever 95 is provided with a laterally directed projection 104, adap ed to cooperate with the arm 88 of armature member 88, as most clearly illustrated in FIG. 2.

A description of the operation of the backspacing mechanism according to the invention will now be given. In the normal rest position of said mechanism, the magnet 32 is de energized, and the armature member 83 is held in its counterclockwise position, as shown in FIG. 3 by spring 85. As a consequence, lever 91 is held (through arms 87 and 89) in its clockwise position against an adjustable eccentric stop 105, and spring 102 tends to urge the composite lever 95 clockwise, thereby causing the lateral projection 104- thereof to abut against the arm 88 of armature 83. In this condition of the mechanism, the interponent 94 is substantially contiguous to the under surface of projection 164. In practice, however. the lever 91 may be constructed of two portions, one portion comprising the interponent 94 and the other portion comprising the abutting surface 196 cooperable with stop 1%, in which event, an adjustment means comparable to that employed in composite lever 39 may be provided.

The laterally directed portion 99 of lever 95 is, in this condition of the mechanism, held out of operative relation with the shoulder 49, thus rendering the constantly reciprocating arm 47 ineffective at this time, since its slot 48 rides freely in the stud 44. Moreover, the member 31 is held in its counterclockwise position against stop 35 by spring 33. Thus, the stud 51 (FIG. 1) is free of the feed pawl arm 29, permitting pawl 24 to engage the feed ratcl'iet 15 to effect normal forward spacing of the tape, as described in the aforesaid Patent No. 2,648,385. Also, the backspace pawl member 54 is clear of the ratchet 15, and the gear rack 70 is holding the rake 69 in its clockwise position, thereby holding the rake projections 71 free of the tape 21. In this condition of operation, normal perforating operation of the apparatus shown in said Patent 2,648,385 may proceed.

A better understanding of the cooperative arrangement of the present improved back spacing mechanism with the punch selecting mechanism of the hereinbefore mentioned United States Patent No. 2,648,385, granted August 11, 1953, to J. L. De Boo, may be had from the following brief description of the apparatus more completely described and illustrated in said United States Patent No. 2,648,385.

As pointed out hereinbefore, the shaft 13 is continuous ly driven and drives a series of five selector cams, of which the cam is representative. A selector lever 165, representative of a group of five selector levers, may be selected for operation by the energization of a selector magnet 127 which controls an armature 128 that blocks clockwise movement (FIG. 8) of the selector levers, such as the selector lever 165, when the selector magnet 127 is tie-energized and which premits the selector levers to follow the contour of their associated cams if the selector magnet 127 is energized. The armature 128 is u ged to rock in a counterclockwise direction by a spring 12?" and in being attracted, against the action of said spring, by the selector magnet 127, effects a selection of one or more of the selector levers each time the cam sleeve, on which the selector cams, such as selector cam 125, goes through a cycle of rotation. The selector magnet 127 is energized and de-energized in accordance with signals received thereby from a distant transmitter, not shown. Normally, when no signals are being received, the magnet 127 is energized and its initial dc-energization, upon receipt of a spacing or start impulse, will permit the cam sleeve, on which the selector cam such as cam 125, are mounted to rotate through one cycle with the shaft 18. After a start signal is received by the selector magnet 127, five permutative marking or spacing impulses are received in timed relation to the presentation of low portions of the selector cams, such as the cam 125, to the cam follower projections on their associated selector levers, such as the selector lever 165. When the selector levers, such as lever 165, are moved in this manner, that is, are permitted to rock clockwise by engaging the low portion of their respective cams, they will move out of the path of a group of selector interponents, such as the selector interponent 171, to permit a spring 176, individual to each selector lever, to rock its associated selector lever in a clockwise direction, to move the right end (FIG. 8) of the selected selector interponent into the path of its associated selector lever, as illustrated by the selector inerponent 171 and selector lever 165. After any selector lever such as lever 165 has been permitted to drop into the low portion of its associated selector cam such as cam 125, a high point on the selector cam will engage the selector lever thus to push its associated selector interponent, such as selector interponent 171, to the left (FIG. 8) to set a punch interponent individual to its, such as the punch interponent 185, in its left-hand position (FIG. 8) where the selected punch interponents will be latched by a latch bail 187 in their left-hand position, as shown in FIG. 8. In each cycle of rotation of the selector cam sleeve with the shaft 18, a permutation code will be set up on the interponents, such as punch interponent 185, and thereafter a selector interponeut restoring bail 156 will be rocked clockwise against the action of its spring 158 to release the selector interponents, such as interponent 171, from their associated selector levers, such as lever 1155. This operation occurs after any of the selector interponents, such as selector interponent 171, have been actuated by their associated selector levers and have moved the punch interponents associated with them, such as the punch interponent 185, to their left-hand positions (FIG. 8).

As the punch interponents 185 were moved to the left, teeth 192 on them slipped beneath the lower edge of the latch bail 187 and consequently were latched by the latch bail, thus to store in the punch interponents, such as punch interponent 185, the permutation code to be perforated in the tape. The selector interponents, such as the interponent 171, may then be restored by bail 156 to position to accept a succeeding code permutation signal. Each of the punch interponents, such as interponent 185, has an extended portion 277 which will be carried into position beneath a shoulder 278 on one of a plurality of punches 244 individual to the punch interponents, such as the punch interponent 1 85. The punches 244 in their normal or rest position are urged to the right (FIG. 8) by contractile springs 243 individual to them to a position where the right side of the upper portion of the punch rests against the guide member 78 and the right side of a lower portion of the punch 244 rests against a comb bar 246.

Adjacent their left ends (FIG. 8), the punch interponents, such as the punch interponent 185, are slidable in a transversely extending portion of a punch bail 291 which is so arranged that the punch interponents, such as punch interponent 1555, may he slid to the right or to the left with respect to the bar 201 into and out of operative association with the shoulders 278. The punch interponents such as interponent 135, are normally urged to the right (FIG. 8) by contractile spring 206 individual to them. Thus any punch interponennsuch as punch interponent 185, which is moved to the left and latched by the latch bail 187, will have its left end (FIG. 8) moved by the bail 291 when the bail 201 is oscillated. The bail 2m is pivoted on pivot bolts 264 and is oscillated at the proper time in the cycle of operation of the apparatus to simultaneously raise any of the punch interponents, such as punch interponent 185, that have been shifted to their left-hand position and locked in that position by the latch bail 187. The selected punch interponents will carry their extended portions 177 into posi tion beneath the shoulder 278 on their associated punches 244 and when the punch bail 2&1 is rocked clockwise (FIG. 8) the selected punches will be driven through a tape in position between the guide blocks 77 and 78.

The actuation of the bail 2M is efiected by the punch actuating toggle mechanism 27 which, when the link 26 is rocked counterclockwise about the shaft 20, will cause 6 the bail 201 to be rocked clockwise about its pivot stud 2tl4. This actuation of the bail 201 is effected by the punch eccentric 222 on the shaft 18. This punch eccentric 222 is clutched to the shaft 18 in the manner described in the aforementioned United States Patent No. 2,648,385 and when the eccentric 222 is clutched to the shaft 18, it will actuate a drive member 223 to first move it to the left and then retract it to the right (FIG. 8). The drive member 223 is pivotally attached to a U-shaped lever 226 which is pivoted about a bolt 227 and has one arm pivotally connected to a link 228. The link 228 is connected to a pivot beam 231 that is in turn pivotally connected to the arm 25 of the link 26 and also pivotally connected to a lever 238 of the toggle mechanism 27. The lever 238 and a second corresponding lever (not shown) are pivotally connected to the punch bail 201 to impart oscillation to the punch bail Zill about its pivot stud 204 each time a cycle of reciprocation is imparted to the link 228.

Now, when it is desired to perform a backspacing operation, the key 107 (schematically shown in FIG. 3) is depressed to close contact 108 to complete an obvious circuit to energize the magnet 82, which upon energization attracts its armature 83 and moves the arm 88 thereof out of the path of the lateral portion 184 of lever 95, and in front of projection 94 (FIG. 3). At the same time, arm 87 of armature 83 merely moves away from arm 89 of lever 91 because projection 94 is still blocked by pro jection 104. The lever 95 is now free to be rotated clockwise by the spring 102, so that now the lateral projection 99 will rest upon the arm 47 of eccentric 17, and upon the next leftward movement of arm 47, the projection 99 will become engaged by the shoulder 49. Arm 47 of eccentric 17 thus is now coupled to lever 39 so that upon the rightward movement of arm 47 (during its reciprocation), lever 39 will be actuated in a counterclockwise direction about pivot 41 to cause, through arm 38 and link 37, the member 31 to be actuated in a clockwise direction. During this movementof member 31, several things occur; namely, (1) the stud 51 acts upon arm 29 to withdraw the advance feed pawl 24 from engagement with ratchet 15; (2) the rack 67 will rotate the rake member 69 (during the initial portion of the rotation of member 31) into the position shown in FIG. 4 to level the lids 71 prior to the backspace movement of the tape 21; and (3) the pawl tooth 55 of pawl member 54 will be brought into coaction with the back of the teeth of ratchet 15 to rotate the ratchet 15 clockwise (as viewed in FIG. 1) to effectuate a backspacing operation.

it is noted that only an initial portion of the rotation of member 31 is used to rotate the rake member 69 into lid-leveling position (FIG. 4). Therefore, to compensate for the further movement of member 31 beyond the amount required to operate rake 69, the rack 67, as previously described, is normally biased clockwise about pivot 59 on the member 31 by its spring 74 and is held against stud 66. This rack 67 moves initially with member 31 as a unit until projections '71 of rake 69 abut the guide 77, whereafter further rotation of pinion 68 is not possible. Thereafter, pursuant to further movement of member 31, the pivot stud 59 will move said member to cause the rack member 67 to rotate counterclockwise (against the pull of its spring 74) about the last tooth of rack 74) (meshed with pinion 63) as a fulcrum, as more clearly shown in FIG. 6.

in order to prevent the pawl 55 from picking up the next tooth before member 31 has fully returned to its counterclockwise position after a backspacing operation I has been completed, the latch 58 is provided, and is eff fective through projection 57 of pawl member 54 to hold said pawl 35 clear of the next tooth on the return stroke shown in FIG. 1. The spring 61 is of such strength as to impart a latching effect between the beveled end of the latch 53 and the projection 57. To procure the proper adjustment between pawl tooth 55 and the teeth of ratchet 15, the clamping means exemplified by the clamping screw 66 is utilized. Thus, the member 64 is rotated counterclockwise until, through the depending portion 65 thereof and the lateral portion 57 of pawl member 54, the pawl member '54 is rotated counterclockwise to establish the proper clearance or relationship between pawl tooth 55 and teeth of ratchet 15, whereupon the clamping screw 66 is tightened.

As indicated hereinbefore, facilities are provided in accordance with the invention, to limit the back-spacing operation to a single step in the event the key 107 is held operated longer than necessary. The instrumentality for achieving this non-repeat feature comprises the inter ponent 94. As shown in the normal rest position of the apparatus in FIG. 3, the lever 95 is blocked by the armature 83, and the interponent 94 is blocked by the lever 95. Then, upon initiation of the power-operated backspace function by the closing of contact 107, the magnet 82 is energized to permit lever 95 to rotate clockwise, but interponent 94 is still blocked by the lever 95. As previously mentioned, the armature 83, upon being attracted, brought the arm 88 thereof out of the path of the lateral portion 104 and in front of projection 94. Now, when the arm 47 of the eccentric 17 was actuated rightwardly it operated the member 31, as previously described, and withdrew the lever 95 away from the arm 88 of armature 83 suificiently to permit the interponent 94 to be presented between said arm 88 and projection 104 of lever 95 under the influence of spring, 162, so that, when arm 47 is again returned to its leftward position, the projection 104 of lever 95 is blocked by the interponent 94, thus causing the lever 95 to rotate counterclockwise to cause the disengagement of projection 99 from the shoulder 49 of arm 47. Then, when contact 197 is again opened, the magnet 82 is de-energized to cause its armature to be released, which, through arm 89 will cause lever 91 to rotate clockwise to remove interponent 94 out of blocking engagement with lever 95 to thereby bring the elements back into the condition shown in FIG. 3.

Although a specific embodiment of the invention has been shown in the drawings and described in the accompanying specification, it is understood that this invention is not limited thereto, but is capable of modification and rearrangement without departing from the spirit and scope of the invention.

What is claimed is:

l. In an apparatus for perforating a control form, means for perforating lidded apertures in said control form, means for moving said control form stepwise in a forward direction, means for moving said control form in a reverse direction, oscillatable means operated by said last-mentioned means for leveling the lids prior to the reverse movement of said control form, and means comprising a pair of attrahently biased members operable to limit the reverse movement of the control form to a single step.

2. In an apparatus for perforating a control form, means for perforating lidded apertures in said control form, a first means for moving said control form stepwise in a forward direction, a second means for moving said control form in a reverse direction, a rotatable rake means for leveling the lids prior to the reverse movement of said control form, rack and pinion means controlled by said second means for operating said rake means, power means for operating said second means, said second means comprising a pair of attrahently biased members, means for controlling the effectiveness of said attrahently biased members to couple one of said members to said power means, and means on the other of said members to 8 limit the reverse stepwise movement of the control form to a single step.

3. In an apparatus for perforating a control form, means for perforating lidded apertures in said control form, a first means for moving said control form stepwise in a forward direction, a second means for moving said control form in a reverse direction, a rotatable rake means for leveling the lids prior to the reverse movement of said control form, rack and pinion means controlled by said second means for operating said rake means, power means for operating said second means, and means for coupling said second means to said power means to effectuate a reverse movement of said control form.

4. In an apparatus for perforating a control form, a

plurality of punches adapted to perforate lidded apertures in the control form, means for moving the punches into and out of a perforating position, means for advancing the control form subsequent to each perforating operation, a mechanism for disengaging said control form advancing means and moving the control form backwards, and oscillatable means operable concurrently with said mechanism for levelling the lids formed during the perforating operation prior to backward movement of the control form to facilitate the backward movement of the control form, said means comprising an electromagnetic device and a constantly operating power operated device raving cooperating facilities to limit the backspacing to a single operation for each actuation of the backspacing mechanism.

5, in a record strip controlling device, means engaglog a record strip to move it in either a forward or reverse direction, means for imparting step-by-step movement to said strip engaging means in a forward direction, and means for imparting step-by-step movement to said strip engaging means in a reverse direction comprising a constantly reciprocating operating arm, a pair of at' trahently biased levers, a latching projection on one of said levers for connecting said one lever to said operating arm for bodily movement thereby, a blocking projection on said one lever, electromagnetically operable means normally engaging said blocking projection to hold said latching projection out of operative association with said operating arm, an interponent portion on the other lever of said pair for normally engaging one surface of said blocking projection on said one lever, a lever assemblage on which said one lever is pivotally mounted and which is operative to move the means engaging the record strip in a reverse direction upon bodily movement of said one lever in one direction, mean for operating said electromagnetically operable means to release said blocking projection and permit the latching projection to engage said operating arm, and a surface on said intcrponent portion of said other lever for engagement by said blocking projection for disengaging said latching projection from said operating arm when said one lever is moved bodily in a second direction by said operating arm if said electromagnetically operable means is held operated.

6. in a record strip controlling device, means for engagement with a record strip to move it in either a forward direction or a reverse direction, means for imparting step-by-step movement to said strip engaging means in a forward direction, and means for imparting step-bystep movement to said strip engaging means in a reverse direction comprising a main backspace member, means on said backspace member for driving engagement with the means for imparting movement to the record strip, means also on said backspace member for disabling the means for driving the strip engaging means in a forward direction, a pair of attrahently biased levers one of which drives the said backspace member, a constantly reciprocating arm for actuating said one lever, a latching projectron on said one lever for connecting said constantly reciprocating arm to said one lever to drive the backspace member, means normally blocking said one lever from connecting relation with said reciprocating arm, means for moving said blocking means out of its normal position to release said one lever, the second lever of said pair of levers being biased to engage said means normally blocking said one lever, and means on said second lever for disengaging said latching projection from said constantly reciprocating arm each time the blocking means is moved out of its normal position thereby to limit the backspace member to a single operation for each actuation of the blocking means.

7. In a record strip controlling device, means engaging a record strip to move it in either a forward or re verse direction, means for imparting step-by-step movement to said strip engaging means in a forward direction, and means for imparting step-by-step movement to said strip engaging means in a reverse direction comprising a constantly reciprocating operating arm, a pair of attrahently biased levers, a latching projection on one of said levers for connecting said one lever to said operating arm, a blocking projection on said one lever, means normally engaging said blocking projection to hold said latching projection out of operative association with said operating arm, an interponent portion on the other lever of said pair for normally engaging one surface of said blocking projection on said one lever, a lever assemblage for moving the means engaging the record strip in a reverse direction, means for operating said means for holding the latching projection to release said blocking projection and permit the latching projection to engage said operating arm, and a surface on said interponent portion of said other lever for engagement by said blocking projection for disengaging said latching projection from said operating arm when said one lever is moved in a second direction by said operating arm if said means for holding the latching projection is held operated, thereby to limit the reverse movement of the record strip to one step each time its operation is initiated.

8. In a record strip controlling device, means for engagement with a record strip to move it in either a forward direction or a reverse direction, means for imparting step-by-step movement to said strip engaging means in a forward direction, and means for imparting step-bystep movement to said strip engaging means in a reverse direction comprising a main backspace member, means on said backspace member for driving engagement with the means for imparting movement to the record strip, means for disabling the means for driving the strip engaging means in a forward direction when said back space member is operated, a pair of attrahently biased levers, linkage means connecting said main backspace member to one of said levers of said pair, said one lever being pivotally connected to said linkage means, a constantly reciprocating arm for actuating said one lever, a latching projection on said one lever for interconnecting it with said constantly reciprocating arm to drive the linkage and backspace member, means normally blocking said one lever from connecting relation with said reciprocating arm, electromagnetically actuated means for moving said blocking means out of its normal position to release said lever, the second lever of said pair of levers being biased to engage said means normally blocking said one lever, and means on said second lever for disengaging said latching projection from said constantly reciprocating arm each time the blocking means is moved out of its normal position thereby to limit the backspace member to a single operation each time the blocking means is moved out of its normal position.

References Cited in the file of this patent UNITED STATES PATENTS 2,255,794 Lake Sept. 16, 1941 2,517,995 Fitch Aug. 8, 1950 2,648,385 De B00 Aug. 11, 1953 

